Many types of disposable consumer products such as diapers, training pants, feminine care articles, incontinence articles, and the like, utilize an absorbent pad structure for absorbing and wicking away bodily fluids. The absorbent pads are conventionally formed from an absorbent web, typically a non-woven fibrous web material. With one particular general practice, the absorbent web is formed by employing conventional airlaying techniques wherein fibers and typically a superabsorbent material are mixed and entrained in an air stream and then directed onto a forming surface to form the web. The absorbent web may then be directed for further processing and assembly with other components to produce a final absorbent article. An advantage of this practice is that trim waste can be immediately recycled by returning the waste to the upstream fiberizing equipment and/or airlaying equipment.
With another conventional technique, preformed absorbent web sheets or layers are delivered into a manufacturing line from a preformed supply, such as a supply roll. The absorbent sheet material may be separated into adjacent strips having various configurations of repeat pattern “nested” shaped pads wherein the shape of one pad is substantially nested with the shape of at least one immediately adjacent pad.
The preformed absorbent material roll process presents particular challenges. For example, the geographical separation of the base roll-making machine makes recycling of the trim waste impractical and cost prohibitive. In this regard, the nesting feature mentioned above has been desirable to reduce the amount of waste that is generated from the originally supplied (roll) of absorbent web. However, with conventional nesting techniques and profiles, a considerable amount of trim waste is still generated.
In some applications, it may be desirable to provide a higher basis weight of absorbent material in the crotch portion as compared to the front and back portions. This has been conventionally done by using a forming surface in an air forming process that contains pockets. The pockets have a depth greater than other portions of the forming surface. Thus, during the air forming process, fibers and absorbent particles collect in the pockets creating greater basis weight areas.
Unfortunately, the pockets cannot be filled completely without overfilling the non-pocket regions. Consequently, the formed fibrous web has to be scarfed in order to remove absorbent material in the non-pocket regions. The scarfed fibrous material is then returned to the forming chamber and reused.
In addition to having to scarf the final product, use of a pocketed forming surface has also other limitations. For instance, basis weight ratios are limited by the process. Further, scarfing cannot practically be performed when various components are contained in the fibrous material that is used to form the absorbent layer. For instance, scarfing is not well suited for absorbent structures with very high superabsorbent material/fluff ratios or absorbents with components such as meltblown fibers, which may be added in certain situations to improve integrity.
The present invention provides a method for producing longitudinally symmetric or asymmetric absorbent pad structures with minimal or zero waste. The pad structures may be formed in an inline process that produces absorbent garments or, alternatively, an absorbent material may first be formed and later converted into the absorbent pad structures of the present invention for use in absorbent garments. The absorbent structures made according to the present invention have high basis weight areas at desired locations.